Place the cucumber slices into a large bowl and set aside.

Thinly slice the red onion and add it to the bowl with the cucumbers.

In a separate bowl, combine the sour cream, lemon juice, chopped dill, sugar, garlic powder, salt, and black pepper.

Whisk the dressing until completely smooth and creamy.

Pour the dressing over the cucumber and onion mixture.

Gently toss everything together until all slices are evenly coated.

Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to blend.

Stir once before serving to redistribute the dressing.

Garnish with additional fresh dill and serve chilled for the best texture and flavor.